The accuracy of restoration of femoral head centre of rotation in the anteroposterior plane after uncemented total hip arthroplasty: a CT-based study

Bone & Joint Research

article

Asim Rajpura¹  Soheil Ghane Asle²  Tarik Ait Si Selmi³  Tim Board⁴ 

[1] Centre for Hip Surgery, Wrightington Hospital;The Northern Hospital;Centre Orthopedique Santy;Orthopaedics, Wrightington Hospital

关键词: Hip;    Arthroplasty;    Biomechanics;    femoral head;    uncemented total hip arthroplasty;    hips;    CT scans;    Femoral anteversion;    proximal femur;    knee;    muscle fibre;    femoral stem;    arthroplasty;   

DOI  :  10.1302/2046-3758.113.BJR-2021-0378.R2

学科分类：骨科学

来源: British Editorial Society Of Bone And Joint Surgery

【 摘 要 】

AimsHip arthroplasty aims to accurately recreate joint biomechanics. Considerable attention has been paid to vertical and horizontal offset, but femoral head centre in the anteroposterior (AP) plane has received little attention. This study investigates the accuracy of restoration of joint centre of rotation in the AP plane.MethodsPostoperative CT scans of 40 patients who underwent unilateral uncemented total hip arthroplasty were analyzed. Anteroposterior offset (APO) and femoral anteversion were measured on both the operated and non-operated sides. Sagittal tilt of the femoral stem was also measured. APO measured on axial slices was defined as the perpendicular distance between a line drawn from the anterior most point of the proximal femur (anterior reference line) to the centre of the femoral head. The anterior reference line was made parallel to the posterior condylar axis of the knee to correct for rotation.ResultsOverall, 26/40 hips had a centre of rotation displaced posteriorly compared to the contralateral hip, increasing to 33/40 once corrected for sagittal tilt, with a mean posterior displacement of 7 mm. Linear regression analysis indicated that stem anteversion needed to be increased by 10.8° to recreate the head centre in the AP plane. Merely matching the native version would result in a 12 mm posterior displacement.ConclusionThis study demonstrates the significant incidence of posterior displacement of the head centre in uncemented hip arthroplasty. Effects of such displacement include a reduction in impingement free range of motion, potential alterations in muscle force vectors and lever arms, and impaired proprioception due to muscle fibre reorientation.

【 授权许可】

CC BY-NC